The invention herein resides in the art of industrial rollers of the type traditionally used for bonding, embossing, curing, or providing a nip to assist in wrapping a web of material about a roll. Prior art industrial rollers of this nature have generally consisted of a steel drum having wrapped thereabout a large solid rubber cover with the cover having a thickness as great as four inches. This roller with the solid rubber cover was typically used as the driven wheel in a roll bight with the web of material passing through the bight being processed as by being bonded, embossed, cured, or the like. In most operations, the roll bight was effectuated by forceful engagement between two rolls, one of which had thereabout the thick solid rubber cover. With such pressure engagement, the rubber cover would tend to flex under compression of the roll bight and, due to the hysteresis effect of the compression and recovery of the rubber, enormous amounts of heat were generated. Such heat would cause the rubber cover to age, crack, and deteriorate rapidly. To prevent such effect on the rubber cover, the roll bight would typically be used at low speeds or external cooling equipment would be used to dissipate the heat generated in the flexing rubber cover. Of course, low operating speeds are undesirable from a manufacturing standpoint, and external cooling equipment adds to both initial and maintenance costs.
Solid rubber covers are also used in winding thin films. In this application the nip roll serves to control the amount of air trapped between wraps. If a solid rubber nip roll cover is soft enough to produce an adequate contact area on the film surface, it often tends to stretch and squirm. With some films this produces loads which cause the product to walk off the wind-up roll.
A number of approaches have been taken to eliminate or significantly reduce the heat generated in the prior art structures. Prior art known to applicant which generally relate to the inventive structure presented hereinafter consists of U.S. Pat. Nos. 689,590; 1,277,995; 3,098,284; 3,253,323; 3,295,188; 3,394,902; 3,460,221; and 3,937,412. Additionally, Canadian Pat. Nos. 653,299; 654,990; 866,062; and 866,063, are also of general interest. A review of the structures of these patents evidences the fact that the art is still void of an industrial roller which is extremely durable in operation while providing a footprint at the roll bight which effects a smooth and uniform forceful engagement with the material being processed.